Passengers already know the routine. An impending storm approaches and airlines begin to cancel flights ahead of the chaos. But unsuspecting flyers might be selling themselves short if they buy the airline's line about what they can or can't do with their tickets.

Most discounted airline tickets carry heavy restrictions. Some are entirely non-refundable or cannot be voluntarily changed. Others allow some flexibility but carry hefty fees that in some cases exceed the original cost of the ticket. When storms cause cancellations and delays, the rules vary by airline and even country, but as planes sit on the ground, passengers could be leaving money on the proverbial table.

Despite some government regulations that allow for compensation for delays and cancellations, passengers are typically out of luck if the cause is due to weather or other unforeseen circumstances. Using Europe and the U.S. as examples, the most passengers can expect in these cases are some token offerings of meal allowances and phone calls or in some cases, accommodations. However, when it comes to your unused tickets, some airlines are more forthcoming than others and this is where it can get confusing for passengers.

Recent winter storms in the northeast United States crippled operations at many of the nation's busiest airports. In anticipation of the storms and in order to have aircraft and crew in their proper locations when operations resumed, airlines began to cancel flights and notify passengers. The good news was that many airlines waived their strict ticket change fees if passengers decided to fly on another day. Passengers were allowed to reschedule up to a certain date in order to avoid the fees. Anytime later and not only would fees apply again, but the difference in fare would also have to be paid. You can give the airlines credit for being proactive and offering a bit of airline fee amnesty, but when it comes to telling passengers about all of the possible options with their tickets, offering a full refund rarely ranks at the top of the list.

In the U.S. and for flights to and from EU member states (and passengers flying on EU based carriers), passengers affected by cancellations can ask for a full refund. And it's not just a ticket credit for a future flight, which itself might have an expiration date. No, passengers are entitled to get their money back for any unused portion of their ticket if they choose not to fly due to a cancelled flight. This is separate from additional compensation that may or may not apply, depending on the circumstances and where the cancellation took place. If a passenger decides not to take or continue his or her journey after a cancellation, a refund can be requested, even for a so-called non-refundable ticket. The same holds true for any baggage fees paid.

When it comes to being bumped from a flight due to overbooking, airlines in Europe and the U.S. are required to compensate passengers based on a set of parameters that must be met. In other words, if the passenger complied with all the airline's rules for checking in and being present for boarding when required and was still bumped, compensation is due. Passengers have the right to request this compensation in cash, not just a travel voucher typically offered by the airline. In addition, a full refund for any unused parts of a ticket can also be requested if the passenger chooses not to travel. The process of getting your money back might not be as quick as you'd like, but it's something you are entitled to and should pursue if you are no longer able to travel because of a cancellation.

Remember to read an airline's conditions of contract (or carriage) and become familiar with what an airline will do in the event of a cancellation. Ask questions before you travel. When chaos ensues, you might find it hard to get an airline agent as willing or able to go over your options in a meaningful way. A blanket of snow might ruin your travel plans, but it shouldn't blind you to the few rights you have as airline passengers – at least in some parts of the world.